Evaluation of the usefulness of non-weight-bearing tunnel view using X-ray in the short term after medial meniscus posterior root tear onset: a retrospective study.

BACKGROUND: This study aimed to examine whether the non-weight-bearing tunnel view X-ray is effective for short-term evaluation of medial meniscus posterior root tear (MMPRT) by assessing the X-ray characteristics at the initial and follow-up visits. METHODS: This was a retrospective longitudinal study of 26 enrolled knees diagnosed with MMPRT on magnetic resonance imaging. The distance between the medial tibial eminence and medial femoral condyle (MTE-MFC distance) and medial tibiofemoral joint (MTFJ) width were measured by obtaining non-weight-bearing tunnel view and frontal view X-ray radiographs. The initial and follow-up values at a median interval of 17 days were compared. Additionally, the correlations between the MTE-MFC distance increase rate and body mass index (BMI), age, femorotibial angle (FTA), and posterior tibial slope (PTS) were evaluated using linear regression analysis. RESULTS: The tunnel view images of the initial and follow-up X-rays showed a significant increase in the MTE-MFC distance and a significant decrease in the MTFJ width. Furthermore, a moderate correlation was observed between the change in the MTE-MFC distance and the time interval between X-rays. However, no substantial correlation was observed for the change in the MTFJ width over time. Moreover, no significant correlation was observed between the change in the MTE-MFC distance in the non-weight-bearing tunnel view and BMI, age, FTA, and PTS. CONCLUSIONS: The non-weight-bearing tunnel view is highly beneficial for evaluating MMPRT progression in the short term.

Male sex, revision surgery, low volume of anterior cruciate ligament remnant, and significant instability are risk factors for Posterior Root Tear of the Lateral Meniscus in patients undergoing Anterior Cruciate Ligament Reconstruction.

PURPOSE: This multicenter study aimed to determine the incidence of lateral meniscus posterior root tears (LMPRTs) in patients undergoing ACL reconstruction and identify associated risk factors. METHODS: We conducted a retrospective, multicenter study using data from the Francophone Arthroscopic Society's registry. The study included all the patients in the registry who underwent ACL reconstruction surgery between June 2020 and June 2023, we excluded incomplete data. We compared delay from injury to surgery between LMPRTs group and No LMPRTs group. Variables investigated as potential risk factors for LMPRTs included age, sex, nature of surgery (primary or revision), pivot shift test result, side-to-side laxity under anesthesia, presence of ACL remnant, occurrence of medial meniscal tear, and presence of collateral ligament injury. Risk factors were analyzed using a logistic regression model. RESULTS: Among the 5359 patients analyzed, LMPRTs occurred in 7.0% (n=375) of cases during ACL reconstruction. Mean age at surgery was 29.3 +/- 10.3 years old [11-77]. Concerning delay to surgery, the mean time was 8.4 +/- 23.1 weeks [0.0-347.2] in the No LMPRTs group and 6.5 +/- 10.2 weeks [0.2-61.6] in the LMPRTs group (p = 0.109). Univariate analysis revealed that male sex (p < 0.001), revision surgery (p < 0.001), medial meniscal injury (p = 0.007), ACL remnant (0% vs > 70%, <10% vs > 70%, 10 to 30% vs > 70%, 30 to 50% vs > 70%, 50 to 70% vs > 70%; p < 0.001) and higher pivot shift grade (p = 0.011) were significantly associated with a presence of LMPRTs. Age, side-to-side laxity, and collateral ligament injury were not found to be significant risk factor In multivariate analysis : male sex, revision surgery, pivot shift test result and a low volume of ACL remnant remained significant. Side to side laxity was also a significant factor in multivariate analysis. CONCLUSION: This study identified male sex, revision surgery, low volume of ACL remnant, side to side laxity and higher grade of pivot shift as significant risk factors for LMPRTs during ACL reconstruction.

Assessing the Frequency and Effectiveness of Various Arthroscopic Treatments in the Management of Symptomatic Isolated Medial Meniscus Injuries Including Medial Meniscus Posterior Root Tear: A Retrospective Observational Cohort Study.

The use of various strategies for arthroscopic meniscal repairs to save the meniscus and prevent the progression of knee osteoarthritis has gradually increased. We investigated the frequency of various arthroscopic treatments and the short-term clinical outcomes of symptomatic isolated medial meniscus (MM) injuries. This retrospective observational study included 193 patients (197 knees) who underwent arthroscopic meniscal treatment for isolated MM injuries between January 2016 and April 2019. Arthroscopic meniscal repairs were divided into two groups: transtibial pullout repairs of MM posterior root tears (MMPRTs) and arthroscopic meniscal repairs for other types of MM injuries. MMPRT pullout repair, other meniscal repairs, and partial meniscectomy were performed in 71.0%, 16.8%, and 12.2% of the knees, respectively. The ratio of women to men and the patient age were higher in the pullout-repair group than the meniscal-repair group. The Preoperative Knee Injury and Osteoarthritis Outcome Score subscale (as an index of daily living activities) was significantly lower in the pullout-repair group than the meniscus-repair group. However, no significant differences were observed in these scores among the two groups postoperatively. Our results suggest that familiarity with the diagnosis and treatment of MMPRTs is necessary for orthopedic surgeons to manage isolated MM injuries.

Accurate tibial tunnel position in transtibial pullout repair for medial meniscus posterior root tears delays the progression of medial joint space narrowing.

PURPOSE: This study aimed to evaluate the association between the progression of medial joint space (MJS) narrowing, medial meniscus extrusion (MME) and clinical scores and the tibial tunnel position in pullout repairs for medial meniscus posterior root tears (MMPRTs). METHODS: This retrospective study examined 54 patients. Changes in MJS (ΔMJS), MME (ΔMME) and clinical scores and their relationship with the tibial tunnel position were evaluated using correlation coefficients. The distance from the anatomical to technical attachment position in the tibial tunnel position was measured in the anterior and medial directions, and the direct distance was measured using the Pythagorean theorem. RESULTS: The mean ΔMJS and ΔMME were 0.6 ± 0.8 and 1.3 ± 1.3 mm, respectively, and the mean anterior, medial and direct distances were 1.4 ± 2.3, 2.2 ± 1.7 and 3.4 ± 1.7 mm, respectively. ΔMJS had a significant positive correlation with the medial (r = 0.580, p < 0.001) and direct (r = 0.559, p < 0.001) distances, while ΔMME had a significant positive correlation with direct distance (r = 0.295, p = 0.030). Several clinical scores were significantly negatively correlated with these distances. CONCLUSION: In transtibial pullout repair for MMPRTs, accurate tibial tunnel position delayed the progression of MJS narrowing and MME, leading to improved clinical outcomes. The progression of MJS narrowing was associated with the mediolateral direction of the tibial tunnel position, while the clinical scores were associated with the anteroposterior direction of the tibial tunnel position. These findings indicate the need to orient the tip of the guide in a more posterolateral direction when creating the tibial tunnel. LEVEL OF EVIDENCE: Level IV.

Intercondylar notch width and osteophyte width impact meniscal healing and clinical outcomes following transtibial pullout repair of medial meniscus posterior root tears.

PURPOSE: This retrospective study aimed to investigate the relationship between intercondylar notch width (ICNW), osteophyte width (OW), and the healing of medial meniscus posterior root tears (MMPRTs) following arthroscopic pullout repair. METHODS: The study included 155 patients diagnosed with MMPRTs who underwent transtibial pullout repair. Meniscal healing status was evaluated on second-look arthroscopy using a previously reported meniscus healing score. Patients were divided into two groups based on this score: the high healing score (group HH, healing score ≥ 8 points) and suboptimal healing score (group SO, healing score ≤ 6 points) groups. Computed tomography scans were performed on patients 1 week postsurgery. ICNW and OW widths were measured and relatively evaluated based on their ratio to the intercondylar distance (ICD), represented as the ICNW/ICD ratio (%) and OW/ICD ratio (%), respectively. Patient-reported outcomes were assessed preoperatively and on second-look arthroscopy using the Knee injury and Osteoarthritis Outcome Score (KOOS) and visual analogue scale (VAS). RESULTS: There were no significant demographic differences between the SO and HH group (n = 35 and 120 patients, respectively). Regarding radiographic measurements, significant differences were observed in the ICNW/ICD ratio (group SO, 24.2%; group HH, 25.2%; p = 0.024), OW (group SO, 2.6 mm; group HH, 2.0 mm; p < 0.001), and OW/ICD ratio (group SO, 3.5%; group HH, 2.7%; p < 0.001). Both groups had similar preoperative clinical scores, but postoperative clinical scores, including KOOS-activities of daily living (group SO, 83.4; group HH, 88.7; p = 0.035) and VAS (group SO, 19.1; group HH, 11.3; p = 0.005), were significantly better in group HH. CONCLUSION: The study suggests that ICNW and OW may play a crucial role in MMPRT healing following arthroscopic pullout repair, as evidenced by the worse clinical outcomes associated with a narrower ICNW and wider OW. These findings highlight the potential significance of ICNW and OW assessments when evaluating meniscal repair indications. LEVEL OF EVIDENCE: Level III.

Meniscal healing status after medial meniscus posterior root repair negatively correlates with a midterm increase in medial meniscus extrusion.

PURPOSE: The second-look arthroscopic score of pullout repair for medial meniscus posterior root tears (MMPRTs) is associated with contemporaneous clinical scores and progression of cartilage damage. However, the relationship among these scores, midterm clinical scores and magnetic resonance imaging (MRI) evaluations is unknown. The relationship between the second-look arthroscopic score at 1 year and the clinical scores or MRI at 3 years was evaluated. METHODS: Sixty-three patients were included. Medial meniscus extrusion (MME) was evaluated preoperatively and at 3 years postoperatively. Clinical scores were evaluated preoperatively, and 1 and 3 years postoperatively. Meniscal healing status was assessed using the semiquantitative second-look arthroscopic score at 1 year postoperatively. Correlation coefficients between patient characteristics, postoperative clinical scores or second-look arthroscopic score and the change in MME (ΔMME) were evaluated. Multiple regression analysis was performed on the ΔMME to evaluate the effects of patient characteristics and second-look arthroscopic scores. RESULTS: No significant correlation was observed between patient characteristics and ΔMME. In contrast, a significant correlation was found between the second-look arthroscopic score and ΔMME (p < 0.001) and visual analogue scale pain score (p = 0.016) at 3 years postoperatively. In the subitems of the second-look arthroscopic score, width (p < 0.001) and stability (p = 0.009) scores also showed significant correlations with ΔMME. Multiple regression analysis showed a significant association between the second-look arthroscopic score and ΔMME (p = 0.001). CONCLUSIONS: The second-look arthroscopic score at 1 year postoperatively correlated with the ΔMME and clinical score at 3 years postoperatively. Second-look arthroscopic scores predict midterm meniscal function after pullout repair of MMPRTs. LEVEL OF EVIDENCE: Level IV.

Identical clinical outcomes between neutral and classic targeted alignments after high tibial osteotomy in medial meniscus posterior root tear: a prospective randomized study.

PURPOSE: This study aimed to compare the clinical and radiographic outcomes and arthroscopic findings after high tibial osteotomy (HTO) between neutral and classic targeted coronal alignments in patients with medial meniscus posterior root tears (MMPRTs). METHODS: Ninety-eight patients with MMPRT were prospectively enrolled in the final cohort and randomized into two groups. Fifty-two patients with the targeted alignment through the Fujisawa point (60-62.5% of the entire tibial plateau width measured from the medial side) during HTO were included in group A, whereas 46 patients with the targeted alignment through the point at 50-55% of the tibial plateau width were included in group B. The clinical and radiographic outcomes and second-look arthroscopic findings were statistically compared for comprehensive assessments. RESULTS: After a mean follow-up of 37.1 months, we found no significant differences between the two groups regarding the final Lysholm (p = 0.205) and Hospital for Special Surgery scores (p = 0.084). However, we only observed significant differences between the two groups in terms of the final hip-knee-ankle angle, weight-bearing line ratio, and medial proximal tibial angle (p < 0.001). Second-look arthroscopy did not reveal a significant difference in meniscal healing rate (p = 0.786). CONCLUSIONS: Performing HTO with the aim to achieve neutral alignment leads to similar clinical outcomes in patients with MMPRT compared to classic alignment. Although subsequent research is required, the current study provides clinical evidence for the safety and efficacy of the new targeted alignment during HTO, which may avoid long-term complications associated with overcorrection when using the traditional technique.

Ultrasonographic diagnosis of medial meniscus posterior root tear in early knee osteoarthritis: a comparative study.

INTRODUCTION: This study aimed to detect medial meniscal posterior root tear (MMPRT) diagnostic methods with high sensitivity and specificity using dynamic ultrasonographic evaluation in patients with early knee osteoarthritis (OA) and demonstrate the usefulness of dynamic ultrasonographic medial meniscal extrusion (MME) evaluation in MMPRT diagnosis using a cutoff value. MATERIALS AND METHODS: Between 2018 and 2020, a total of 120 patients were diagnosed with early knee OA using clinical and radiographic findings. Dynamic ultrasonographic evaluations and magnetic resonance imaging were performed in all patients, and 47 patients who had and 73 patients who did not have MMPRT were classified into the MMPRT and non-MMPRT groups, respectively. Age, sex, femorotibial angle, MME of knee extension and flexion, and MME at weight-bearing were compared between the two groups. Additionally, the sensitivity and specificity of significant ultrasonographic findings were calculated using a receiver operating characteristic (ROC) curve. RESULTS: The MMEs under knee extension-flexion and weight-loading in the MMPRT group were significantly larger than those in the non-MMPRT group. ROC curve analysis for each ultrasonographic evaluation condition to diagnose MMPRT indicated that the sensitivity was 72-88% and the specificity was 66-85% when the cutoff values of MME under knee flexion at 0°, 90°, and weight-loading were set at 2.55 mm, 2.00 mm, and 3.55 mm, respectively. The highest sensitivity (88%) and specificity (85%) were exhibited upon > 2 mm MME at a knee flexion of 90° and were the most useful indicators for MME diagnosis. CONCLUSIONS: Ultrasonographic MME evaluations for MMPRT diagnosis showed relatively high sensitivity and specificity in patients with early knee OA. Dynamic ultrasonographic MME evaluation may lead to appropriate additional examinations, early diagnosis, and intervention for MMPRT in patients with early knee OA.

Longitudinal changes in medial meniscus extrusion and clinical outcomes following pullout repair for medial meniscus posterior root tears: a 3-year evaluation.

PURPOSE: We aimed to evaluate the longitudinal changes in medial meniscus extrusion (MME) and clinical scores at multiple time points up to 3 years after pullout repair for medial meniscus posterior root tears (MMPRTs). METHODS: This retrospective case series study included 64 patients who underwent pullout repair for MMPRTs and four MRI evaluations (preoperatively and at 3 months, 1 year, and 3 years postoperatively). MME was measured during the same time points. Clinical scores were assessed four times: preoperatively and at 1, 2, and 3 years postoperatively. Additionally, a multivariate analysis was performed on the change in MME (ΔMME) from the preoperative measurement point to 3 years postoperatively. RESULTS: The ΔMME per month from the preoperative measurement point to 3 months postoperatively, from 3 months to 1 year postoperatively, and from 1 to 3 years postoperatively were 0.30, 0.05, and 0.01 mm/month, respectively. All clinical scores significantly improved 3 years postoperatively (p < 0.001). In a multiple regression analysis for ΔMME from the preoperative measurement point to 3 years postoperatively, sex significantly affected the outcome (p = 0.039). CONCLUSION: Following pullout repair for MMPRTs with well-aligned lower extremities, although MME progression could not be entirely prevented, the rate of progression decreased over time, and clinical scores improved. In particular, MME progressed markedly during the first 3 months postoperatively. Additionally, sex had a significant influence on MME progression, suggesting that males may be able to expand the indications of pullout repair for MMPRTs.

Development and Analysis of Mouse Medial Meniscus Posterior Root Tear Model.

Medial meniscus posterior root tears (MMPRT) are often associated with osteoarthritis (OA) progression and subchondral bone insufficiency fractures. This study aimed to develop the first MMPRT mouse model. The MMPRT model was created by sectioning the medial meniscus posterior root of 12-week-old CL57BL/6J male mice under stereomicroscopic observation. The sham operation and the destabilization of the medial meniscus (DMM) model groups were also created. OA progression and subchondral bone changes were evaluated histologically using the Osteoarthritis Research Society International (OARSI) subchondral bone scoring system at 2, 4, 8, and 12 weeks after surgery. Microcomputed tomography (µCT) was performed to evaluate the presence of insufficient fractures. OA progression and medial meniscus extrusion were observed in the MMPRT and DMM models 12 weeks after surgery. OA progressed in both models during the time course, without a significant difference in the OARSI score between the two groups. The subchondral bone score was significantly higher at 12 weeks than at 2 and 4 weeks in the MMPRT group, while no significant difference was found between the two groups. In the µCT analysis, destruction of the medial tibial plateau was observed in 4/40 knees, while none were observed in the DMM group. Of the four knees, destruction of the medial femoral condyle was also observed in three knees. Characteristic pathological changes were observed in the mouse MMPRT model. The mouse MMPRT model may be useful for investigating pathological changes after MMPRT.

Increased quadriceps muscle strength after medial meniscus posterior root repair is associated with decreased medial meniscus extrusion progression.

BACKGROUND: This study aimed to assess quadriceps muscle strength after medial meniscus (MM) posterior root repair and determine its relationship with clinical scores and MM extrusion (MME). METHODS: Thirty patients who underwent pullout repair for MM posterior root tear and were evaluated for quadriceps muscle strength preoperatively and at 1 year postoperatively were included in this study. Quadriceps muscle strength was measured using the Locomo Scan-II instrument (ALCARE, Tokyo, Japan). MME and clinical scores (i.e., Knee Injury and Osteoarthritis Outcome Score [KOOS], International Knee Documentation Committee score, Lysholm score, Tegner score, and visual analog scale pain score) were evaluated preoperatively and at 1 year postoperatively, and second-look arthroscopy was performed at 1 year postoperatively. Wilcoxon's signed-rank test was used to compare each measure pre- and postoperatively. Pearson's correlation coefficient was used to assess the correlation with quadriceps muscle strength values. Multiple regression analysis was performed to identify factors associated with the change in MME (ΔMME). RESULTS: Second-look arthroscopy confirmed continuity of the posterior root in all patients. The quadriceps muscle strength measured at 1 year postoperatively (355.1 ± 116.2 N) indicated significant improvement relative to the quadriceps muscle strength measured preoperatively (271.9 ± 97.4 N, p < 0.001). The MME at 1 year postoperatively (4.59 ± 1.24 mm) had progressed significantly relative to the MME preoperatively (3.63 ± 1.01 mm, p < 0.001). The clinical scores at 1 year postoperatively were improved significantly relative to the scores preoperatively (p < 0.001). The postoperative quadriceps muscle strength was correlated with ΔMME (correlation coefficient = -0.398, p = 0.030), and the change in quadriceps muscle strength was correlated with the KOOS-Quality of Life (correlation coefficient = 0.430, p = 0.018). Multiple regression analysis showed that the postoperative quadriceps muscle strength had a significant effect on ΔMME even when the body mass index and time from injury to surgery were included. CONCLUSIONS: After MM posterior root repair, patients with greater quadriceps muscle strength showed less MME progression. In addition, patients with greater improvement in quadriceps muscle strength had better clinical scores; therefore, continued rehabilitation aimed at improving quadriceps muscle strength after MM posterior root repair is recommended. LEVEL OF EVIDENCE: IV.

The efficacy of medial meniscal posterior Root tear Repair with or without high tibial osteotomy: a systematic review.

BACKGROUND: Medial meniscal posterior root tear (MMPRTs) is a common lesion of the knee joint, and repair surgery is a well-established treatment option. However, patients with obvious varus alignment are at an increased risk for MMPRT and can suffer from a greater degree of medial meniscus extrusion, which leads to the development of osteoarthritis following repair. The efficacy of high tibial osteotomy (HTO) as a means of correcting this malformation, and its potential benefits for MMPRT repair, remains unclear. PURPOSE: To explore whether HTO influenced the outcome of MMPRT repair in clinical scores and radiological findings. STUDY DESIGN: Systematic review. METHODS: According to the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analyses) guidelines, we searched PubMed, Embase, Web of Science, and the Cochrane Library databases for studies reporting the outcomes of MMPRT repair and extracted data about characteristics of patients, clinical functional scores and radiologic outcomes. One reviewer extracted the data and 2 reviewers assessed the risk of bias and performed a synthesis of the evidence. Articles were eligible if they reported the results of MMPRT repair with exact mechanical axis (registered in the International Prospective Register of Systematic Reviews, CRD42021292057). RESULTS: Fifteen studies with 625 cases of high methodological quality were identified. Eleven studies were assigned to the MMPRT repair group (M) with 478 cases performing MMPRT repair only, and others belonged to the MMPRT repair and HTO group (M and T) performing HTO and MMPRT repair. Most of the studies had significantly improved clinical outcome scores, especially in M groups. And the radiologic outcomes showed that the osteoarthritis deteriorated in both groups with similar degree in about 2-year follow-up. CONCLUSION: HTO is a useful supplement in treating MMPRT patients with severe osteoarthritis and the clinical and radiological outcomes were similar with MMPRT repair alone. Which would be better for patients' prognosis generally, performing MMPRT repair alone or a combination of HTO and MMPRT repair, was still controversial. We suggested taking K-L grade into account. Large-scale randomized control studies were called for in the future to help make better clinical decisions. LEVEL OF EVIDENCE: III.

Subchondral insufficiency fracture is a predictive factor of osteoarthritis progression and conversion to arthroplasty in non-surgically treated medial meniscus root tear.

PURPOSE: To investigate the radiographic and clinical outcomes of non-surgical treatment for medial meniscus posterior root tear (MMPRT), and prognostic factors for osteoarthritis (OA) progression and clinical failure. METHODS: A prospectively collected database was retrospectively reviewed for patients who were diagnosed with acute medial meniscus posterior root tear (MMPRT) between 2013 and 2021 and treated non-surgically for more than 2 years. Patient demographic characteristics and clinical outcomes including pain numeric rating scale (NRS), International Knee Documentation Committee (IKDC) subjective score, Lysholm score, and Tegner activity scale were evaluated. For radiographic evaluation, knee radiographs were obtained to assess the angle of knee alignment and Kellgren-Lawrence (K-L) grade during the first and annually follow-up visits. Baseline magnetic resonance (MR) images were reviewed for the presence of medial meniscus extrusion, bone marrow edema, subchondral insufficiency fracture of medial femoral condyle, and cartilage lesion. The OA progression group was defined as patients who experienced a worsening of one or more grades in the K-L classification system. Prognostic factors were evaluated for OA progression and conversion to total knee arthroplasty (TKA). RESULTS: Ninety-four patients (90 female and 4 male) with a mean age of 67.0 ± 7.3 years (range, 53-83 years) were followed for a mean of 46.1 ± 22.1 months (range, 24.1-170.5). During the follow-up period, no significant differences in clinical scores were observed, and there were also no significant differences between the groups with and without OA progression. Overall, 12 patients (13%) underwent TKA at a mean of 20.7 ± 16.5 months (range, 8-69 months) and 34 patients (36%) demonstrated OA progression at a mean time of 24 ± 15 months (range, 12-62). The subchondral insufficiency fracture was a prognostic factor for OA progression (p = 0.045 for knee radiograph and p = 0.019 for MR) and conversion to TKA (RR, 4.08 [95% CI 1.23-13.57]; p = 0.022). CONCLUSIONS: Non-surgical treatment for acute medial meniscus posterior root tear did not result in any significant change in clinical outcomes from the initial to the final follow-up. The rate of conversion to arthroplasty was 13%, and the rate of osteoarthritis progression was 36%. Furthermore, subchondral insufficiency fracture was found to be a concomitant prognostic factor correlated with OA progression and conversion to arthroplasty. This information can provide insights for physicians when discussing treatment options with patients, particularly regarding the use of non-surgical treatment and may contribute as a source for future studies of medial meniscus posterior root tear. LEVEL OF EVIDENCE: IV.

Steep posterior slope of the medial tibial plateau and anterior cruciate ligament degeneration contribute to medial meniscus posterior root tears in young patients.

PURPOSE: Medial meniscus posterior root tears (MMPRTs) occur most frequently in middle-aged and older adults. However, this serious condition can also occur in younger patients. The purpose of this study was to compare anterior cruciate ligament (ACL) degeneration and sagittal medial tibial slope in young adults with and without MMPRT. METHODS: Eighteen healthy volunteers, 18 young patients (20-49 years of age), and 30 middle-aged and older patients (50-70 years of age) with MMPRT repair were included in the study. Sex, body mass index (BMI), femorotibial angle, ACL degeneration, and medial tibial slope angle were compared among the groups. ACL degeneration and medial tibial slope angle were assessed using magnetic resonance imaging. RESULTS: In the healthy volunteer group, the young patient group, and the older patient group, the medial tibial slopes were 3.5° ± 1.4°, 6.1° ± 2.7°, and 7.2° ± 1.9°, respectively, and the ACL degeneration rates were 5.6%, 38.9%, and 43.3%, respectively. Young patients with MMPRT had significantly steeper medial tibial slopes and ACL degeneration compared to those of the healthy volunteers (P < 0.05). The parameters of young patients were similar to those of older patients with MMPRT. In the multivariate logistic regression analysis, BMI, medial tibial slope, and ACL degeneration were significantly associated with MMPRT in young patients. CONCLUSION: BMI, steep medial tibial slope, and ACL degeneration contribute to MMPRT development in younger patients. LEVEL OF EVIDENCE: Level III.

The clinical and radiographic outcomes of type 2 medial meniscus posterior root tears following transtibial pullout repair.

PURPOSE: The aim of this study was to compare the clinical outcomes of different subtypes of type 2 medial meniscus posterior root tears following transtibial pullout repair. METHODS: In total, 147 patients (mean age: 66.2 ± 8.3 years) who were diagnosed with type 2 medial meniscus posterior root tears and underwent transtibial pullout repair were included. Patients were divided into 2A (n = 31), 2B (n = 90), and 2C (n = 26) groups according to tear type. Clinical outcomes were assessed pre-operatively and at second-look arthroscopy using the Knee injury and Osteoarthritis Outcome Score. The meniscal healing status was evaluated at second-look arthroscopy. Medial meniscus extrusion was calculated using magnetic resonance imaging pre-operatively and at second-look arthroscopy. RESULTS: No significant differences in pre-operative or post-operative clinical scores were observed between each subtype, although clinical scores improved post-operatively for each subtype. Significant differences were noted in the anteroposterior width of the bridging tissues at second-look arthroscopy (2A, 7.1 ± 1.2; 2B, 6.2 ± 1.7; and 2C, 6.2 ± 1.7 mm; p = 0.045); type 2A tears were the widest. There was a significant difference in post-operative medial meniscus extrusion (2A, 3.2 ± 0.9; 2B, 4.0 ± 1.2; and 2C, 4.0 ± 1.4 mm; p = 0.004) and its progression (2A, 0.7 ± 0.6; 2B, 1.2 ± 0.8; and 2C, 1.2 ± 0.8 mm; p = 0.008), and type 2A tears were the shortest. CONCLUSION: Although there was no significant difference in the post-operative clinical scores among different type 2 tears in the short term, type 2A tears showed better healing and medial meniscus extrusion progression prevention, thus indicating the usefulness of classifying tear type in estimating post-operative outcomes. LEVEL OF EVIDENCE: III.

Insufficient restoration of meniscal extrusion by transtibial pullout repair for medial meniscus posterior root tears.

PURPOSE: The long-term changes in the dynamics of the medial meniscus after transtibial pullout repair for medial meniscus posterior root tears (MMPRTs) are not completely understood. Thus, the aim of this study was to investigate the effects of transtibial pullout repair on MMPRTs and whether the effects would be sustained. METHODS: Nineteen knees with MMPRTs that were treated by trans-tibial pullout repair were enrolled in this study. Medial meniscus extrusion (MME) was measured by ultrasonography during knee extension (no weight-bearing with the knee at 0° extension: NW0°) and 90° flexion (no weight-bearing with the knee at 90° flexion: NW90°) with the patient in the supine position and with full weight-bearing (FW0°) preoperatively and at 3 and 12 months postoperatively. The clinical outcomes were assessed using the Knee Injury and Osteoarthritis Outcome Score, Lysholm score, and International Knee Documentation Committee score. RESULTS: The difference in MME with NW0° was not statistically significant between the preoperative (3.4 ± 1.0 mm) and 12-month postoperative (3.7 ± 0.6 mm) time points. The MME with NW90° at 3 (2.1 ± 0.7 mm) and 12 months (2.9 ± 0.6 mm) postoperatively were significantly lower than the preoperative values (3.4 ± 0.8 mm) (P < 0.05). However, the value significantly increased from 3 to 12 months postoperatively (P < 0.05). The MME with FW0° at 12 months postoperatively (4.3 ± 0.6 mm) was significantly larger than that at pre-operatively (3.6 ± 0.9 mm) (P < 0.05). All the patients' clinical conditions were significantly improved at 12 months postoperatively when compared to their preoperative clinical conditions. CONCLUSION: Surgery did not reduce the extrusion in the no weight-bearing and weight-bearing positions at knee extension, and these values increased in the postoperative period. In addition, while the surgery reduced the extrusion in the knee flexion position, the restoration achieved by the surgery was not sustained in the long term. LEVEL OF EVIDENCE: Level IV.

Lateral-medial asymmetry of posterior tibial slope and small lateral tibial plateau articular surface depth are morphological factors of lateral meniscus posterior root tears in ACL-injured patients.

PURPOSE: To investigate whether knee morphological features, patient characteristics, and intraoperative findings are associated with a lateral meniscus (LM) posterior root tear (LMPRT) in anterior cruciate ligament (ACL) injuries with the integrated data from two academic centres. METHODS: This retrospective study used registry data acquired prospectively at two academic centres. Patients with ACL reconstruction (ACLR) with LMPRT and no other LM injury were selected (LMPRT group) from each database. The control group included patients who underwent ACLR without LM tears. Patients were matched to the LMPRT group according to age and gender (1:1). Morphological factors evaluated on preoperative magnetic resonance image scans included lateral femoral condyle (LFC) anterior-posterior diameter, height, and depth; lateral tibial plateau (LTP) articular surface (AS) depth and sagittal plane depth; and lateral and medial posterior tibial slopes (PTSs). LFC height and depth ratios, LTP AS depth and sagittal plane depth ratios, and lateral-to-medial slope asymmetry were computed from previous measurements. Patient characteristics and intraoperative findings were extracted and compared between both groups. RESULTS: The study included 252 patients (126 in each group). The lateral-medial asymmetry of PTS was greater in the LMPRT group (1.2° vs 0.3°, p < 0.05), and the LTP AS depth was smaller in the LMPRT group (31.4 mm vs 33.2 mm, p < 0.01). There were no differences in LFC morphology between the control and LMPRT groups. Pivot shift grade (p < 0.05), percentage of complete ACL tears (p < 0.05), and medial meniscus ramp lesions (p < 0.05) were significantly higher in the LMPRT group. CONCLUSION: LMPRT was associated with significantly increased lateral-medial asymmetry of PTS and significantly smaller LTP AS depth. LMPRT was also associated with an increase in the preoperative pivot shift grade and the presence of a medial meniscus ramp lesion. These morphological characteristics are rather simple to measure and would serve as helpful indicators to preoperatively detect LMPRT, which is frequently challenging to diagnose preoperatively. LEVEL OF EVIDENCE: Level III.

Repair of medial meniscus posterior root tear is effective for root healing and cartilage regeneration in opening wedge high tibial osteotomy.

PURPOSE: This study aimed to determine whether the repair of a medial meniscus posterior root tear (MMPRT) is effective for MMPRT healing, cartilage regeneration, and clinical outcomes in opening wedge high tibial osteotomy (OWHTO). METHODS: This retrospective study included 80 patients who underwent OWHTO and subsequent second-look arthroscopy. The patients were divided into OWHTO-with-MMPRT-repair (n = 40) and OWHTO alone (n = 40) groups, and the healing rates (complete/partial/failure) were compared. Each group was further divided into over- and under-corrected subgroups to compare healing rates. The International Cartilage Repair Society (ICRS) grade, cartilage defect size, Koshino stage, ICRS cartilage repair assessment score of the medial femoral condyle (MFC), and International Knee Documentation Committee (IKDC) scores between the OWHTO-with-MMPRT-repair and OWHTO alone groups were compared according to whether microfracture was performed on the MFC. RESULTS: The overall healing rate of the MMPRT was higher in the OWHTO-with-MMPRT-repair group than that in the OWHTO alone group (P < 0.001). In addition, in the subgroup analysis, no difference in the MMPRT healing rate between the over-correction and under-correction groups when MMPRT repair was performed (n.s). In contrast, without MMPRT repair, the healing rate was lower in the under-correction group than that in the over-correction group (P = 0.03). Cartilage regeneration of the OWHTO-with-MMPRT-repair group was superior to that of the OWHTO alone group (P < 0.05). The IKDC subjective scores of the OWHTO-with-MMPRT-repair and OWHTO alone groups were 34.5 and 33.1 before surgery (n.s) and 50 and 47.2 at one year after surgery, respectively (n.s). These differences between the two groups for cartilage regeneration and IKDC subjective scores showed the same pattern regardless of microfractures. CONCLUSIONS: MMPRT repair during OWHTO might improve MMPRT healing, even with under-correction, and cartilage regeneration of MFC, regardless of microfracture. However, OWHTO with MMPRT repair might not improve short-term clinical outcomes compared to OWHTO alone. Further randomized clinical trials are necessary. LEVEL OF EVIDENCE: III, Retrospective cohort study.

Epidemiological features of acute medial meniscus posterior root tears.

PURPOSE: Untreated or overlooked medial meniscus posterior root tears (MMPRTs) induce sequential knee joint degradation. We evaluated epidemiological features of acute MMPRT for its early detection and accurate diagnosis. METHODS: Among 330 MMPRT patients from 2018 to 2020, those who underwent arthroscopic pullout repairs were enrolled. Patients who underwent non-operative treatment or knee arthroplasty, those with a cruciate ligament-deficient knee or advanced osteoarthritis of the knee, and those with insufficient data were excluded. Finally, we retrospectively evaluated data from 234 MMPRTs (female: 79.9%, complete tears: 92.7%, mean age: 65 years). Welch's t-test and Chi-squared test were used for pairwise comparisons. Spearman's rank correlation analysis was performed between age at surgery and body mass index (BMI). Multivariable logistic regression analysis with stepwise backward elimination was applied to the values as risk factors for painful popping events. RESULTS: In both sexes, there were significant differences in height, weight, and BMI. In all patients, there was a significant negative correlation between BMI and age (ρ = - 0.36, p < 0.001). The BMI cutoff value of 27.7 kg/m2 had a 79.2% sensitivity and a 76.9% specificity for detecting MMPRT patients aged < 50 years. A painful popping event was confirmed in 187 knees (79.9%), and the frequency was significantly reduced in partial tears as compared to complete tears (odds ratio: 0.080, p < 0.001). CONCLUSION: Higher BMI was associated with a significantly younger age of MMPRT onset. Partial MMPRTs had a low frequency of painful popping events (43.8%).

Medial joint space narrowing progresses after pullout repair of medial meniscus posterior root tear.

PURPOSE: The extent to which arthropathic changes progress after medial meniscus posterior root tear (MMPRT) repair remains controversial. This retrospective study assessed medial joint space (MJS) narrowing progression after pullout repair for MMPRT and identified the correlating factors. METHODS: We included 56 patients who underwent pullout repair for MMPRT. The MJS of the bilateral knees was assessed with radiography using the fixed-flexion view. A second-look arthroscopy was performed one year post-operatively for all patients. The baseline characteristics, clinical scores, Kellgren-Lawrence (KL) grade, and medial meniscus extrusion (MME) were identified. Statistical comparisons and correlation analyses were conducted. RESULTS: The MJS narrowing width was significantly larger in MMPRT knees than in contralateral knees (0.51 ± 0.85 mm vs. 0.09 ± 0.49 mm, p < 0.001). KL grade progression was observed in 23.2% (13/56) of patients. There was a significant difference between pre- and post-operative MME values, indicating MME progression (p < 0.001). Each clinical score showed significant improvement one year post-operatively (p < 0.001). Positive correlations were found between MJS narrowing and pre-operative MJS (coefficient = 0.510, p < 0.001), rate of change in MJS (coefficient = 0.929, p < 0.001), and increase in MME (ΔMME) (coefficient = 0.506, p < 0.001). CONCLUSION: Knees that underwent pullout repair for MMPRT showed progression of MJS narrowing by 0.51 mm at one year post-operatively, although clinical scores markedly improved. Correlating factors for MJS narrowing were pre-operative MJS, rate of change in MJS, and ΔMME. Preventing MME progression is essential for preventing arthropathic changes.